The other two top Republican contenders, Chris Dahlberg and state Sen. Julianne Ortman, pledged to abide by the party endorsement. McFadden said he was headed to an August primary no matter what, and state Rep. Jim Abeler could go that route, too.

The endorsement of McFadden is good news for Republicans who want to train their sights on Franken instead of wading into a bruising primary battle.

Republicans typically endorse candidates who pledge to adhere to the party endorsement. But Luke Yurzyk, a Sartell Republican activist, said McFadden offers Republicans the best chance to win in November.

Yurzyk said McFadden's ability to raise millions for his campaign is critical.

"His ability to fundraise is phenomenal," Yurzyk said. "Certainly with Al Franken, who is a good fundraiser himself, we're going to need the resources."

Dahlberg, a St. Louis County commissioner, jumped out to a surprise lead Friday in the early rounds of endorsement voting at the Minnesota GOP state convention at Mayo Civic Center.

But McFadden reversed the narrative after voting dragged on into Saturday. Rep. Michele Bachmann endorsed McFadden early Saturday, shortly before he cemented the endorsement.

Dahlberg conceded just before the 10th round of voting results were announced. GOP delegates held a voice vote shortly afterward to formally endorse McFadden.

A scratchy-voiced McFadden clutched his throat as he thanked delegates, saying his endorsement win "is only the end of the beginning."

"I look forward to taking the fight to Al Franken," McFadden said.

Delegates cast seven rounds of ballots Friday, with Dahlberg the leader in all of them. But he couldn't reach the 60 percent threshold to secure the endorsement.

McFadden gained significant ground on the eighth ballot Saturday, vaulting into a near-tie with Dahlberg. He surpassed Dahlberg on the ninth ballot, paving the way for him to secure the endorsement in Round 10.

Ortman didn't reach a needed threshold to remain in the mix. She stopped short of ending her campaign outright.

Dahlberg said an underdog like him could match up well against Franken. Dahlberg also stressed his standing as a Republican in northeastern Minnesota, where Democrats usually run up big numbers.

McFadden, who's never held an elected office but has already scooped up millions in campaign donations, stressed that outsider status as he repeatedly said voters aren't enamored of either party's record in Washington.

"We've created a professional class of politicians, and it is killing us, and Republicans are as bad as Democrats," he said. "I'm as far from a professional politician as you can find."

Ken Wolf, a delegate from Burnsville, decided in recent weeks to go with McFadden over Ortman. He said he just wants a fall winner, something the party has had trouble finding in recent years in statewide races.

"People have said whether you win or lose you make a statement," Wolf said of those past picks. "I say when you lose, you make no statement at all."

The sharpest barbs were reserved for Franken, the Democrat who squeaked into office after a recount and court case in which he edged Republican Sen. Norm Coleman by 312 votes. They blamed him for the health insurance law requiring people carry coverage because his election provided a crucial 60th Senate vote. And they said he hasn't stood up to President Barack Obama when it counted.

Franken was headed to Duluth for his party's convention on Saturday, where he faces no opposition for the party's endorsement.